A sample of what such a manifest could look like is here:
https://gist.github.com/despens/d6ae4110c4e97944ddba29f23d78899f
It could be served at a predictable location for each wikibase instance - such as, for instance,
https://www.wikidata.org/manifest-v0.1.json
or something similar

One other approach to this problem would be to consider that these manifest files are not expected to be necessarily hosted by the Wikibase instance itself - these configuration files could be user-contributed and hosted anywhere (or derived automatically from the Wikibase Registry). The downside is that this requires more work from the community (users need to maintain these manifest files themselves) but it could be necessary if we want to include things like URLs of external tools like QuickStatements.

For reference:
The IDs the constraint checker needs are here: https://github.com/wikimedia/mediawiki-extensions-WikibaseQualityConstraints/blob/master/extension.json

The config they've used is explained here: https://github.com/wikimedia/mediawiki-extensions-WikibaseQualityConstraints#data-import

I have tried to to this using this Wikibase instance: https://arbaso.wiki.opencura.com/. I find a problem following the instructions here (https://github.com/wetneb/openrefine-wikibase) with Redis. It seems that there is an error with INCRBYFLOAT.

redis.exceptions.ResponseError: unknown command 'INCRBYFLOAT'

But it could be my own problem!

@Theklan let's move your issue to a different ticket as your issue does not seem to be related: T240436

If the manifest has to be constructed by hand, it seems like YAML would be a better format than JSON. They are equivalent from a structural and informational point of view, but YAML is much easier to edit without creating invalid documents.

Excited to see the Wikibase team picking up this issue. I am tagging this ticket with the corresponding project, hoping that this is appropriate?